Estimation of Fatigue Crack Growth at Transverse Vibrations of a Steam Turbine Shaft

IntroductionOperation of steam turbine structural elements is characterized by heavy mechanical and thermal loading in corrosive environment. One of the main consequences of such operation conditions is the fatigue damage of steam turbine structural elements, which accumulates for a long time and finally develops into local damage of a fatigue crack type.MethodsTo estimate the fatigue crack growth rate in steam turbine shaft in the process of transverse vibrations when rotor passes through the first critical speed the analytical model has been developed. As a model object, the high-pressure rotor of the K-210-130 steam turbine was chosen. The durability of cracked rotor in terms of start-ups number was estimated with the fracture mechanics theory based on the calculated stresses in the cracked area, as well as on the experimentally determined crack growth rate for the rotor steel.ConclusionCrack growth relationships were established depending on the size of the initial crack, angular acceleration of the rotor, and a number of other parameters. The angular acceleration, rotor's eigenfrequency and damping have the most essential impact on the intensity of crack growth.